This invention relates to rolls of convolutely wound paper, such as bathroom tissue and kitchen towel (also called household towel). More particularly, the invention relates to a coreless roll of such paper.
It is well known in the art that rolls of convolutely wound paper are typically formed on a machine known as a rewinder. A rewinder is used to convert large parent rolls of paper into smaller sized rolls of bathroom tissue, kitchen towel, hardwound towel, industrial products, and the like. A rewinder line consists of one or more unwinds, modules for paper finishing (e.g., embossing, printing, perforating), and a rewinder at the end for winding the paper into a long roll, commonly referred to as a log. Typically, the rewinder produces logs which are about 90 to 180 mm in diameter for bathroom tissue and kitchen towel and about 100 to 350 mm in diameter for hardwound towel and industrial products. Log length is usually about 1.5 to 5.4 m, depending on the width of the parent roll. The logs are subsequently cut transversely to obtain small rolls about 90 to 115 mm long for bathroom tissue and about 200 to 300 mm long for kitchen towel and hardwound towel.
Traditionally these types of paper products are produced and supplied to the end user with a cardboard core at the center. However, as evidenced by numerous patents on the subject, there is a compelling interest in a good way to produce and supply these products without cores. The reasons generally entail potential greater efficiency and less material usage. In the case of center-pull products, the core must be discarded before the product is even used.
Recently the European Union issued a directive stating that cardboard cores inside tissue products are to be considered part of the packaging. They are therefore subject to a tax proportionate to their weight. This is a government program to incentivize the use of less packaging materials. Converters who can supply coreless products will gain a competitive advantage.
Nonetheless, despite their appeal, coreless products remain only a niche in the market. Wider adoption is stalled due to the limitations of coreless production, primarily the overall inefficiency of current coreless rewinders.
Ideally the market would like a coreless production system with the following attributes:                Can produce both low firmness and high firmness rolls, i.e., has a large operating window        Has capital cost and space requirements similar to machines that run with cores.        Has operating costs (consumables and maintenance) similar to machines that run with cores.        Requires operator training and skill level similar to machines that run with cores.        Can operate reliably at high web speed and cycle rate.        Can be quickly and easily switched between production with and without cores.        